Energizing circuits for vacuum tubes



. 2 Nov. i 19 J, 5. GARVIN ENERGIZING CIRCUITS FdR VACUUM TUBES Filed Dec. 18, 1920 I lnvenfoh" I Johh dGarv/m Y Patented Nov. 2, 1926.

STATES PATENT JOHN S. GARVIN, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y.,- A CORPORATION OF NEW YORK.

ENEBGIZIIENG CIRCUITS FOR VACUUM T'UBES.

Application filed December 18, 1920. Serial-No. 431,536.

This invention relates to energizing circuits for vacuum tubes of the type having an anode and an electrically heated cathode, an obj ect of the invention being to supply cathode heating current and space current for such a vacuum 'tube from non-adjustable sources of voltage. A further object is to obtain relatively high voltage space current and relatively low voltage cathode heating current from two electromotive forces each of which is too high for application to the cathode and too low to properly supply the space current.

A further object of the invention is to obtain the requisite low and high voltage cathode and space currents of a vacuum tube amplifier, and also a potential diflerence between the cathode and the control electrode of the amplifier, from two electromotive forces each of which is too high for application to the cathode and too low to'properly supply the space current.

' The system of this invention is especially useful on battle-ships, where the source of 5 supply is a 120 and 240 volt dynamo. In accordance with the invention, such a source may be used to energize an amphfier'in such a manner that no battery is required, even though an electromotive force of, 120 volts is too low forthe plate circuit and too high to be applied to the filament. However, the

system ofthe invention is capable of various.

other applications.

Fig. 1 of the accompanying drawing i s .a diagram of an embodiment of the invention in which the sources of elec roinotive force are indicated as batteries. Fig. 2 of the drawing shows diagrammatically another embodiment of the invention, the source of supply being three-wire dynamo-electric generating apparatus.

.7 In Fig. 1,-vacuum t bes are connnected in I parallel. An input transformer for the tubes is shown at 6, and an output trans former'at 7. An adjustable by-passfor the tubes is indicatedat 9. The plate circuit of each of the tubes is from; a battery 10 through a lead .11; through the pr mary ofthe output transformer 7, to the anode of the tube, through the tube to the cathode, through lead 12 including a resist- 'ancea13',*th1oi1gh a battery 15 and a lead 16 back to the battery 10; The filament of each of the tubes is heated bycurrent pass ng.

from: the-batteryf15 through a. lead 17, in

eluding a resistance 18, through the filament of the tube, through the lead 12 including the resistance 13, and back to the battery 15.

In this system the electromotive force of each of the batteries 10 and 15 may be, for

instance, of .the order of 120 volts, even though such voltage is too high to be ap' plied to the filament and too low to properly supply the space current for the tube. For I the voltage drop in the resistance 18 due to the filament heating currents from the battery 15, plus the electromotive force of the battery 10, is the'electromotive force applied across the anode and the high potential end of the filament, and the difference between the electromotive force of the battery 15 and the sum of the voltage drops in resistances of the filaments and the value of the negative potential desired on the grids. For the negative'potential applied to the grids will be equal to the voltage drop in 13 due to the filament heating currents from the battery 15. The total filament heating currents may be, for instance, of the order of 10,, amperes and the negative potential on the grids may be of the order of 25 volts. Then the re sistance 13 will be 2.5 ohms. necessary to make the resistance of 18 of such a value that the electromotive force of the battery 15 divided by the sum of the resistance of 18, the resistance of the heated filaments in parallel and the resistance of 13 will be equal to the desired total filament heating current. That is, the electromotive force of the battery 15 minus the drop across It will then be for the filament current and drop, the .negative grid potential, and the voltage of battery .15,- the dropin 18 will be about (25+8 :87 volts. Therefore. the voltage applie across the anode-and hi hpotential end of the cathode of each tube is 120-|- 87=,'- 207 volts, which is ample. 3

In Figure 2 the source of supply is shown by way of example as a three-wiresystem comprising dynamos 20 and 25 instead of the dynamo 20 through a leadll, through the batteries and of Fig. 1. Moreover in Fig. 2there, is no resistance connected between ,the negative pole of the dynamo 25 and the filament, for obtaining a negative grid potential; and instead of a resistance common to the tubes 5 for obtaining sufficiently low. voltage for 'the filaments and sufficiently high voltage for application across theanodes and filaments, resistances 28"individual to. the tubes are used. The plate 'circuit of each of the tubes 5 is from the primary winding of the output transformer 7 to the anode of the tube, through the tube to the cathode, through lead 12,

through the dynamo 25 and back to the dynamo 20. The filament of each of" the tubes 5 is heated by current passing from the generator 25 through the lead 17 including. the resistance 28 individual to the tube, through the filaments of the tube, and through the lead 12 back to the dynamo 25. Additionaltubes 35 are shown as connected in parallel with each other, transformer 7 serving as an input transformer for these tubes and a transformer 40 serving as an output transform r; The dynamos 20 and supply the sp ce current and the filament heating current for tubes The plate circuit of each of the tubes 35 is from the dynamo 20 through a lead 51, through the primary winding-of the output transformer n) the anode of-the tube, through the tube to the cathode, through a lead 52, the lead 12, and the dynamo 25 back to the dynamo 20. The filament of each of the tubes 35 is heated by current passing from the generator 25 through the lead 17, through a lead 57 including resistance 48 individual to theltube, through the filament of the tube, and through leads 52 and 12 back to the dynamo 25. Resistances 48 perform' the same function in connection with these tubes that resistances 28 -perform in. connection with tubes 5. .That is, because of the drops due to filament heating currents in 28 and 48, the electromotive forces applied to the filaments of tubes 5 and 35 are substantially lower than vthe electromotive force ofthe d namo 25, and the-electromotive force app ied across the anode and the filament of each of the tubes 5 and 35 is substantially What is claimed is:

higher than the electromotive force of the dynamo 20. The dynamos 20 and 25 are intended to represent anyv well known type of three-wire dynamo-electric generatingapparatus.

having a cathode adapted to be electrically.

heated, said cathode having two terminals, and means for supplying electromotive force to said tube, said means comprising a source having its positive pole connected to said anode, a source having its negative terminal connected toone of said terminals, and a lead including. a resistor connecting the other poles of said sources to the other of said two terminals, said resistor being of" such value as to materially increase the electromotive force between said anode and said other terminal.

3. A vacuum. tube having an anode, a

cathode adapted to be electrically heated and a control electrode, two sources of electromotive force, means connected between said sources and said tube for applying to said cathode an electromotive force substantially lower than the electromotive force of either source and impressing between the anode and the cathode an electromotive force substantially higher than the electromotive force of either source and lower than the electromotive force of the combined loo sources, said means comprising a resistor,

two terminals at different potentials an means comprising a resistor connecting said two terminals across said anode and one of said cathode terminals, andan impedance connected etween said third terminal and the other of said cathode terminals, said impedance being of such valueth'at the electromotive forc supplied to said; cathode is small in comparison to that across any'two of the three terminals-of said source, and

a connection from ,said resistor to said control electrode, for impressing upon said.

electrode a negative potential 'derived from the drop in said resistors 5. *A-vacuum tube having an anode arid having a cathode adapted to be electrically heated, two sources for heating the cathode and supplying space current for the tube, and means for connecting said sources to said tube and maintaining the point of highest potential on the cathode at a potential lower than the lowest potential of one of said sources by an amount equal to a large portion of the voltage of said source, said means including a resistance element in the space current path of said tube.

6. A vacuum tube having an anode',-a cathode adapted to be electrically heated and a control electrode, two sources for supplying electromotive force for. heatin said cathode, sending space current throng said tube and charging said control electrode, and means including resistors for connecting said sources to said anode,-cathode and control electrode, maintaining the point of highest potential on said cathode at a potential lower than the lowest potential of one of said sources by an amount equal to a lar eportion ofthe voltage of said source an maintaining said control electrode at a potential lower than the point of lowest potential'on said cathode.

vacuum tube having an anode and having a cathode with two terminals, a current generator having two terminals at different potentials and a third terminal at a potential between the potentials of said two terminals, leads from said two generator terminals to said anode and one terminal of said cathode, respectively, and a lead including a resistor connecting said third generator terminal with the other cathode terminal, said resistor being of such value that the voltage across said cathode, is small in comparison ta the voltage between said third of said devices.

current, parallel connections from the separate anodes to said common source of space' current and a resistance common to the cathode heating and anode. circuits of all 9. In combination, a plurality of space discharge devices, each having a cathode adapted to be heated and an anode, a common source of space current for said devices and a common source of cathode heating current, said cathode being connected in parallel across said common source of heating current, (parallel connections from the separate ano es to said common source of space current, an' resistance means common to thecathode heating circuit and the space current circuit of each of said devices of such magnitude that the potential drop therethrough comprises a large part of the voltage of said heating current source.

In witness-whereof, I hereunto subscribe my name this 16th day of December, A. D 1920.

JOHN s. GARVIN. 

